Make failure report a little friendlier

If configuration fails by not finding GTest when testing was turned on,
complete successfully and warn about the lack of GTest and provide a reference
to the cmake script to download from GitHub.

Author: steve-downey

CMakeLists.txt

@@ -28,18 +28,26 @@ target_sources(
 )
 
 if(OPTIONAL_ENABLE_TESTING)
+  find_package(GTest QUIET)
+  if(GTest_FOUND)
     # Create the library target and named header set for testing beman_optional
     # and mark the set private
     add_executable(beman_optional_test)
     target_sources(
-        beman_optional_test
-        PRIVATE
-            FILE_SET beman_optional_test_headers
-            TYPE HEADERS
-            BASE_DIRS tests
+      beman_optional_test
+      PRIVATE
+      FILE_SET beman_optional_test_headers
+      TYPE HEADERS
+      BASE_DIRS tests
     )
-
+    # Tests
     add_subdirectory(tests/beman/optional)
+  else()
+    message(WARNING "
+No provider for GTest. Unable to build tests.
+Consider using CMAKE_PROJECT_TOP_LEVEL_INCLUDES=./cmake/use-fetch-content.cmake as documented in the README.md
+")
+  endif()
 endif()
 
 add_subdirectory(include/beman/optional)

cmake/use-fetch-content.cmake

@@ -149,7 +149,7 @@ function(BemanOptional_provideDependency method package_name)
                     "to FetchContent logic fetching ${BemanOptional_repo} at "
                     "${BemanOptional_tag} according to ${BemanOptional_lockfile}."
                 )
-                message(DEBUG "${BemanOptional_debug}")
+              message(STATUS "${BemanOptional_debug}")
                 FetchContent_Declare(
                     "${BemanOptional_name}"
                     GIT_REPOSITORY "${BemanOptional_repo}"
@@ -161,12 +161,13 @@ function(BemanOptional_provideDependency method package_name)
 
                 # Important! <PackageName>_FOUND tells CMake that `find_package` is
                 # not needed for this package anymore
+                message(STATUS "setting ${BemanOptional_pkgName}_FOUND to true")
                 set("${BemanOptional_pkgName}_FOUND" TRUE PARENT_SCOPE)
             endif()
         endif()
     endforeach()
 
-    set(GTest_FOUND TRUE PARENT_SCOPE)
+    # set(GTest_FOUND TRUE PARENT_SCOPE)
 endfunction()
 
 cmake_language(

tests/beman/optional/CMakeLists.txt

@@ -3,40 +3,36 @@
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 # cmake-format: on
 
-find_package(GTest REQUIRED)
-
-# Tests
-target_sources(
-    beman_optional_test
-    PRIVATE
-        optional.t.cpp
-        optional_constexpr.t.cpp
-        optional_monadic.t.cpp
-        optional_range_support.t.cpp
-        optional_ref.t.cpp
-        optional_ref_monadic.t.cpp
-)
-
-target_sources(
-    beman_optional_test
-    PRIVATE
-        FILE_SET beman_optional_test_headers
-        TYPE HEADERS
-        FILES test_types.hpp test_utilities.hpp
-)
-
-target_link_libraries(
-    beman_optional_test
-    PRIVATE beman_optional GTest::gtest GTest::gtest_main
-)
-
-# Issue #32: Re-enable ASAN run CI/clang-19.
-#
-# Note: clang-19 + gtest_discover_tests + Asan setup causes errors on some
-# platforms. Temporary switch to gtest_add_tests and skip some Asan checks.
-# Change also applied for CI flows.
-include(GoogleTest)
-gtest_add_tests(TARGET beman_optional_test "" AUTO)
+ target_sources(
+     beman_optional_test
+     PRIVATE
+         optional.t.cpp
+         optional_constexpr.t.cpp
+         optional_monadic.t.cpp
+         optional_range_support.t.cpp
+         optional_ref.t.cpp
+         optional_ref_monadic.t.cpp
+ )
+
+ target_sources(
+     beman_optional_test
+     PRIVATE
+         FILE_SET beman_optional_test_headers
+         TYPE HEADERS
+         FILES test_types.hpp test_utilities.hpp
+ )
+
+ target_link_libraries(
+     beman_optional_test
+     PRIVATE beman_optional GTest::gtest GTest::gtest_main
+ )
+  # Issue #32: Re-enable ASAN run CI/clang-19.
+  #
+  # Note: clang-19 + gtest_discover_tests + Asan setup causes errors on some
+  # platforms. Temporary switch to gtest_add_tests and skip some Asan checks.
+  # Change also applied for CI flows.
+  include(GoogleTest)
+  gtest_add_tests(TARGET beman_optional_test "" AUTO)
 
 add_library(constructor_fails test_constructor_fail.cpp)